1. Field of the Invention
The present invention relates to a thermal switch, specifically to a thermal-switch instant starter for a fluorescent light which can instantly initiate a high voltage across its electrodes.
2. Description of the Prior Art
As shown in FIGS. 1 and 2, the prior art hereby teaches the structure of a glow starter which comprises an insulating casing 1 having therein a high voltage initiating tube 2, being filled with compressed inert gases such as neon or argon and provided a fixed electrode 3 and a movable electrode 4. Referring to FIG. 2, the glow start is then connected with a fluorescent tube 5 and incorporated with a ballast 6 which is for initiating a high voltage across the two electrodes 3 and 4. When the power is turned on, a potential difference exists between two filaments 5a and 5b of the fluorescent tube 5 and the ballast 6, and between the fixed electrode 3 and the movable electrode 4 of the high voltage initiating tube 2 of the glow starter (GS). The fixed and movable electrodes 3 and 4 start to discharge because the power voltage is higher than the discharge voltage at the high voltage initiating tube 2. During discharging, the movable electrode 4 is gradually heated to expand to contact the fixed electrode 3. And thus, the preheating circuit is completed between the filaments 5a and 5b of the fluorescent tube 5 and the ballast 6. The filaments 5a and 5b of the fluorescent tube 5 is then gradually heated. Immediately after the connection of the electrodes 3 and 4, the discharging of the high voltage initiating tube 2 stops, then the movable electrode 4 will be gradually cool down and break off the contact. Because of the sudden change in current, a high induced voltage is created in the ballast 6 to cause the filaments 5a and 5b to discharge electrons. Finally, the fluorescent tube 5 is turned on.
According to the above-mentioned structure, the two electrodes 3 and 4 are in a normal open status, and when they are connected to form a short circuit by means of discharging process, the preheating current will be provided for the filaments 5a and 5b of the fluorescent tube 5. Only after the filaments 5a and 5b of the fluorescent tube 5 absorb a sufficient amount of heat energy, the ballast 6 can be induced by the disconnection operation of the electrodes 3 and 4 to provide a high voltage. Therefore, the fluorescent tube 5 requires more time (about 4 seconds) to be turned on. In the beginning, just after initiation, the discharging process of the electrodes 3 and 4 does not make a stable connection; and this will reduce the service life of the fluorescent tube 5.